In vivo direction of CD4 T cells to Th1 and Th2-like patterns of cytokine synthesis

Abstract

Factors that influence the initial development, and continued maintenance, of Th1 or Th2-like responses in vivo play a pivotal role in determining immune effector mechanisms and clinical outcome. Here, we review recent developments in this area with particular emphasis on (i) the ability of chemically modified exogenous antigens to preferentially activate Th1- dominated responses in vivo and (ii) the role played by NK cells in initial commitment of naive exogenous antigen-specific T cell to Th1 and Th2-like cytokine synthesis. We find that NK cell depletion of naive mice prior to immunization with OVA (which induces balanced Th0 like responses), or a high Mr polymer (that preferentially elicits OVA-specific Th1-dominated responses), fails to influence the development of cytokine or specific antibody responses. The results argue that NK cells do not play an essential role in shaping induction of immune responses to exogenous antigens, the most common class of inhalant allergen.